Digital Core Supply in Automotive FC-BGA Package: a Smart Modularity Solution for Design and Validation

The growing complexity of automotive digital applications requires a constant evolution of IC and package technologies. Thanks to its flexibility in supporting high signals density, TE-FCBGA (Thermal Enhanced Flip Chip Ball Grid Array) is the current package solution for high-end digital devices. An emerging criticality for this platform is the increasing static current consumption together with decreasing voltage levels, in particular for digital core supply interconnections. This work describes an innovative methodology for power supply optimization at package level, exploiting the concept of design modularity. The first step is to identify an overall layout strategy, working in a co-design context thanks to a close cooperation between package and silicon development engineers. The die to package connection of core supply is typically localized in the central bump-out area and benefits of intrinsic symmetry and uniformity, which are key features for current distribution robustness. This allows to define the ideal package interconnection as a matrix of small equal portions (modules) and to work on a single module that becomes the basic brick of the final layout. The optimization of the single module ensures a more efficient design flow and allows an early estimation of the overall electrical performance, which is obtained by simulation and represents a pre-layout strategy validation. The second step is the full design implementation: at this stage, the uniformity of modular structure can be locally affected by different layout constraints. Post-layout electrical simulation is hence needed to evaluate the impact of non-idealities and quantify the mismatch against early prediction: this drives a layout refinement in the finalization phase. The target is the best trade-off between performance and technology complexity, resulting in package costs optimization.